| commit | f221b8435cfb71e54062f6c6e99e9ade30b124d5 | [log] [tgz] |
|---|---|---|
| author | Jordan Liggitt <liggitt@google.com> | Wed Oct 02 14:33:36 2019 -0400 |
| committer | Gustavo Niemeyer <gustavo@niemeyer.net> | Wed Oct 02 18:33:36 2019 +0000 |
| tree | 2d8d3286ec2f789a7c50b6e77060071c26c5e577 | |
| parent | bb4e33bf68bf89cad44d386192cbed201f35b241 [diff] |
Improve heuristics preventing CPU/memory abuse (#515) This addresses the following items: ==== Parse time of excessively deep nested or indented documents Parsing these documents is non-linear; limiting stack depth to 10,000 keeps parse times of pathological documents sub-second (~.25 seconds in benchmarks) ==== Alias node expansion limits The current limit allows 10,000% expansion, which is too permissive for large documents. Limiting to 10% expansion for larger documents allows callers to use input size as an effective way to limit resource usage. Continuing to allow larger expansion rates (up to the current 10,000% limit) for smaller documents does not unduly affect memory use. This change bounds decode operations from alias expansion to ~400,000 operations for small documents (worst-case ~100-150MB) or 10% of the input document for large documents, whichever is greater.
The yaml package enables Go programs to comfortably encode and decode YAML values. It was developed within Canonical as part of the juju project, and is based on a pure Go port of the well-known libyaml C library to parse and generate YAML data quickly and reliably.
The yaml package supports most of YAML 1.1 and 1.2, including support for anchors, tags, map merging, etc. Multi-document unmarshalling is not yet implemented, and base-60 floats from YAML 1.1 are purposefully not supported since they're a poor design and are gone in YAML 1.2.
The import path for the package is gopkg.in/yaml.v2.
To install it, run:
go get gopkg.in/yaml.v2
If opened in a browser, the import path itself leads to the API documentation:
The package API for yaml v2 will remain stable as described in gopkg.in.
The yaml package is licensed under the Apache License 2.0. Please see the LICENSE file for details.
package main import ( "fmt" "log" "gopkg.in/yaml.v2" ) var data = ` a: Easy! b: c: 2 d: [3, 4] ` // Note: struct fields must be public in order for unmarshal to // correctly populate the data. type T struct { A string B struct { RenamedC int `yaml:"c"` D []int `yaml:",flow"` } } func main() { t := T{} err := yaml.Unmarshal([]byte(data), &t) if err != nil { log.Fatalf("error: %v", err) } fmt.Printf("--- t:\n%v\n\n", t) d, err := yaml.Marshal(&t) if err != nil { log.Fatalf("error: %v", err) } fmt.Printf("--- t dump:\n%s\n\n", string(d)) m := make(map[interface{}]interface{}) err = yaml.Unmarshal([]byte(data), &m) if err != nil { log.Fatalf("error: %v", err) } fmt.Printf("--- m:\n%v\n\n", m) d, err = yaml.Marshal(&m) if err != nil { log.Fatalf("error: %v", err) } fmt.Printf("--- m dump:\n%s\n\n", string(d)) }
This example will generate the following output:
--- t:
{Easy! {2 [3 4]}}
--- t dump:
a: Easy!
b:
c: 2
d: [3, 4]
--- m:
map[a:Easy! b:map[c:2 d:[3 4]]]
--- m dump:
a: Easy!
b:
c: 2
d:
- 3
- 4